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x86: convert cpu_to_apicid to be a per cpu variable

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This patch converts the x86_cpu_to_apicid array to be a per cpu
variable. This saves sizeof(apicid) * NR unused cpus.  Access is mostly
from startup and CPU HOTPLUG functions.

MP_processor_info() is one of the functions that require access to the
x86_cpu_to_apicid array before the per_cpu data area is setup.  For this
case, a pointer to the __initdata array is initialized in setup_arch()
and removed in smp_prepare_cpus() after the per_cpu data area is
initialized.

A second change is included to change the initial array value of ARCH
i386 from 0xff to BAD_APICID to be consistent with ARCH x86_64.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Mike Travis
2007-10-19 20:35:03 +02:00
committed by Thomas Gleixner
parent dbeb2be21d
commit 71fff5e6ca
12 changed files with 80 additions and 22 deletions
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23
arch/x86/kernel/smpboot_64.c
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@@ -694,7 +694,7 @@ do_rest:
clear_node_cpumask(cpu); /* was set by numa_add_cpu */
cpu_clear(cpu, cpu_present_map);
cpu_clear(cpu, cpu_possible_map);
x86_cpu_to_apicid[cpu] = BAD_APICID;
per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID;
return -EIO;
}
@@ -840,6 +840,26 @@ static int __init smp_sanity_check(unsigned max_cpus)
return 0;
}
/*
* Copy apicid's found by MP_processor_info from initial array to the per cpu
* data area. The x86_cpu_to_apicid_init array is then expendable and the
* x86_cpu_to_apicid_ptr is zeroed indicating that the static array is no
* longer available.
*/
void __init smp_set_apicids(void)
{
int cpu;
for_each_cpu_mask(cpu, cpu_possible_map) {
if (per_cpu_offset(cpu))
per_cpu(x86_cpu_to_apicid, cpu) =
x86_cpu_to_apicid_init[cpu];
}
/* indicate the static array will be going away soon */
x86_cpu_to_apicid_ptr = NULL;
}
/*
* Prepare for SMP bootup. The MP table or ACPI has been read
* earlier. Just do some sanity checking here and enable APIC mode.
@@ -849,6 +869,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
nmi_watchdog_default();
current_cpu_data = boot_cpu_data;
current_thread_info()->cpu = 0; /* needed? */
smp_set_apicids();
set_cpu_sibling_map(0);
if (smp_sanity_check(max_cpus) < 0) {